The present invention relates to impact action devices utilized in the mining and construction industries for breaking rock and other materials, for ramming and tamping purposes, for driving in pins and nails, for driving through holes in soil, etc. and, more particularly, it relates to an impact action device wherein the impact member is propelled by the combustion of a combustible matter in the combustion chamber of the device.
At present, an impact action device is known having a housing which receives therein a sleeve and an impact member mounted for reciprocation of the housing and having an enlarged front portion and a tail portion.
The enlarged front portion of the impact member defines with the housing a buffer chamber, while the tail portion of the impact member, when introduced into the sleeve, defines therewith a combustion chamber within the sleeve. This lastmentioned chamber periodically communicates with a source of combustible matter to propel the impact member through a working stroke, as well as with the ambient atmosphere to exhaust the products of combustion.
However, this known impact action device is of a relatively complicated structure and includes a relatively great number of components of different weights, movable relative to one another, which results in rapid wear of these components. Thus, the known device includes an ignition means mounted on the housing thereof and associated with a source of power supply to produce a spark for igniting the combustible mixture in the combustion chamber. The source of power supply circuit is periodically closed by one of the movable components mounted on the impact member.
The ignition device is expected to meet relatively strict requirements, as to reliability and accuracy. However, it is rather difficult to meet these requirements in a device operating in an impact mode. The natural wear of the movable components of the ignition means is aggravated by the wear brought about by great dynamic loads caused by this impact mode of operation. This leads to a short life for the ignition means, to delayed timing of production of a spark and to faulty operation of the impact device, as a whole.
To start the operation of the impact action device of known design, it is necessary to employ an auxiliary mechanism to effect an initial stroke of the impact member, sufficient for compression and ignition of the cobmustible matter in the combustion chamber. More often than not, such an auxiliary starting mechanism is mounted directly on the housing of the impact mechanism.
In the hitherto known impact action devices the exhaust opening for the products of combustion is situated either in the lateral surface of the mechanism, or else in the front face thereof.
Furthermore, the arrangement of the ignition and starting devices directly on the housing of the impact device results in a considerable increase in the transverse dimensions of the device, as a whole, while the arrangement of the exhaust opening in the lateral surface of the impact device and in the front face thereof prohibits the use of the device for driving through holes in soil.
At present, compressed pneumatic impact action devices for driving through holes in the soil, are also known which are, however, incapable of self-sustained operation, since they need an air compressor and means for carrying this air compressor to the site of operation.